Credit

Caption

Orchid starch grains. Polarised light micrograph of a transverse section through an orchid tuber (Phaius grandifolius), showing the starch grains. Starch is made from sucrose, a sugar formed in the leaves during photosynthesis, which is then transported to the tuber (potato) by the phloem (vascular tissue). Starch is used as a source of energy for a growing plant. Magnification: x44 when printed at 10 centimetres wide.